Many control devices are presently required relative to the production and/or distribution of energy sources such as hydrocarbons. Oftentimes, valves are caused to block a pipeline, as a function of the pressure within such line. A typical example would include an actuator causing valve opening or closing, such actuator in turn being controlled by a relay such as described by this invention, and such relay's operation being governed by a signal, hydraulic or pneumatic, received from a line pressure sensitive device, such as a pilot. Most prior art devices, after causing valve closure on loss of pilot signal occurring, have automatically caused valve re-opening, on the return of a pilot signal to the device. For various safety reasons, however, it has become most desirable to require manual resetting of the device after pilot signal failure in order to cause valve re-opening, rather than permit the mere return of pilot signal to cause such opening, i.e., to require a fail-safe lockout. Recent attempts at such an arrangement are exemplified by U.S. Pat. Nos. 3,877,484; 3,963,050; and 3,943,974. The present invention is intended to accomplish such a goal in a more efficient and economical manner.